System for detecting two X-ray energies

Claim 1

A system comprising an X-ray source, an elongate detector tube and a slit diaphragm between the X-ray source and the detector tube, the slit-shaped aperture of the diaphragm extending parallel with the longitudinal axis of the detector tube and the detector tube including at least one cathode extending in the longitudinal direction of the tube and at least one anode located opposite to the cathode and likewise extending in the longitudinal direction of the tube, the tube being evacuated and, during operation, an electrical field being established between the cathode and the anode, characterized in that a filter is mounted near the slit diaphragm in the path between the X-ray source and the detector tube, which filter intercepts a portion of the X-ray beam emitted by the source over the entire length of the slit-shaped aperture and blocks relatively low energy X-radiation in said beam portion, and the cathode is provided with an X-ray detection layer consisting of two essentially parallel strips extending in the longitudinal direction of the tube, one of said strips receiving the radiation passed by the filter and the other of said strips receiving the unfiltered radiation.

Claim 2

A system comprising an X-ray source, an elongate detector tube and a slit diaphragm between the X-ray source and the detector tube, the slit-shaped aperture of the diaphragm extending parallel with the longitudinal axis of the detector tube and the detector tube including at least one cathode extending in the longitudinal direction of the tube and at least one anode located opposite to the cathode and likewise extending in the longitudinal direction of the tube, the tube being evacuated and, during operation, an electrical field being established between the cathode and the anode, characterized in that a filter is mounted near the slit diaphragm in the path between the X-ray source and the detector tube, which filter intercepts a portion of the X-ray beam emitted by the source over the entire length of the slit-shaped aperture and blocks relatively low energy X-radiation in said beam portion, and the cathode is provided with an X-ray detection layer consisting of two essentially parallel strips extending in the longitudinal direction of the tube, one of said strips receiving the radiation passed by the filter and the other of said strips receiving the unfiltered radiation.

Claim 7

A system according to at least one of the preceding claims, characterized in that the X-ray detection layer is of CsI.

Claim 8

A system according to at least one of the preceding claims, characterized in that a strip-shaped region is formed between the thicker strip and the thinner strip of the detection layer, which region is non-responsive to X-radiation.

Claim 9

A system according to one of the preceding claims, characterized in that the anode is composed of two strips, each strip being essentially in registry with one of the strips of the detection layer on the cathode, and one strip of the anode being provided with a phosphor layer adapted to produce light of a first color and the other strip of the anode being provided with a phosphor layer adapted to produce light of a second color.

Claim 10

A system according to one of claims 1-7, characterized in that the anode is provided with a phosphor layer on which two strips of filtering material are so mounted that each strip is essentially in registry with one of the strips of the detection layer on the cathode.

Claim 12

A system according to one of claims 1-7, characterized in that the anode is mounted on the face of a glass fiber plate that faces the cathode, and that additional glass fiber elements are provided on the face of the glass fiber plate that is remote from the cathode, through which elements the image produced by the first strip of detection material can be passed to at least a first diode array and the image produced by the second strip of detection material can be passed to at least another diode array.